A new instrument to quantify firebrand dynamics during fires with particular focus on those associated with the Wildland-Urban Interface (WUI) has been developed. During WUI fires, firebrands can ignite spot fires, which can rapidly increase the rate of spread (ROS) of the fire, provide a mechanism by which the fire can pass over firebreaks and are the leading cause of structure ignitions. Despite this key role in driving wildfire dynamics and hazards, difficulties in collecting firebrands in the field and preserving their physical condition (e.g. dimensions and temperature) have limited the development of knowledge of firebrand dynamics. In this work we present a new, field-deployable diagnostic tool, an emberometer, designed to provide measurement of firebrand fluxes and information on both the geometry and the thermal conditions of firebrands immediately before deposition by combining a visual and infrared camera. A series of laboratory experiments were conducted to calibrate and validate the developed imaging techniques. The emberometer was then deployed in the field to explore firebrand fluxes and particle conditions for a range of fire intensities in natural pine forest environments. In addition to firebrand particle characterization, field observations with the emberometer enabled detailed time history of deposition (i.e. firebrand flux) relative to concurrent in situ fire behaviour observations. We highlight that deposition was characterised by intense, short duration “showers” that can be reasonably associated to spikes in the average fire line intensity. The results presented illustrate the potential use of an emberometer in studying firebrand and spot fire dynamics.

已经开发出一种新的工具来量化火灾期间的火灾烙印动态，特别关注与荒地-城市界面（WUI）相关的火灾。在WUI火灾中，烙印可以点燃局部火势，从而可以迅速提高火势蔓延（ROS）的速度，提供一种机制，使火势能够越过防火区，并且是导致建筑物着火的主要原因。尽管在推动野火动态和危害方面发挥了关键作用，但在野外收集火柴并保存其物理状况（例如尺寸和温度）方面的困难限制了火柴动态知识的发展。在这项工作中，我们提出了一种新的，可现场部署的诊断工具，一种血栓仪，通过结合使用可见光和红外热像仪，可在沉积之前立即测量火印通量并提供有关火印几何和热状况的信息。进行了一系列实验室实验，以校准和验证已开发的成像技术。然后，将栓塞仪部署到野外，以探索天然松树林环境中各种火势的火星通量和颗粒状况。除了对火印颗粒进行表征外，与同时进行的原地火行为观察相比，用火化仪进行的野外观测还可以提供详细的沉积时间历史（即火印通量）。我们强调沉积的特点是强烈，持续时间很短的“阵雨”，可以合理地与平均火线强度的峰值相关。给出的结果说明了在研究火烙印和现场火势动力学中使用电火花计的潜在用途。